One of the biggest challenges athletes face when competing or training, particularly in moderate to hot temperature conditions, is heat. Not only must the athlete cope with heat from the external environment, but he/she also must cope with heat generated within his/her own body as a result of physical exertion.
Substantial heat may be generated in a person's body as a result of physical activity and exertion. In general, a body's core temperature rises with increased physical activity. Less than 25% of the energy created during physical activity is converted into work energy (e.g., energy used to move the body and/or resist an applied force). The remaining 75%+ of the created energy typically must be dissipated as released heat. The human body's most effective mechanism for dealing with excess heat is through evaporative cooling. When a person's core body temperature rises to a certain level, the body will start to sweat. When this liquid sweat evaporates, the physical conversion of the liquid to its corresponding gas form (i.e., the drying) draws heat from the nearest heat source. In the case of sweat, the nearest heat source is the skin. In this manner, sweating cools a person due to the evaporative cooling action as the sweat dries. This evaporation of sweat is dependent upon the water vapor pressure (or relative humidity) of the air in contact with the skin. Air movement also is an important factor. For example, ambient air gains humidity as it picks up moisture during the evaporation of sweat. In the absence of adequate air movement (ventilation), this humidified air becomes trapped in areas surrounding the skin, thus inhibiting the cooling provided by the continued evaporation of sweat.
Failure to properly release and move heat away from the body during exercise in a warm environment can cause a dangerous rise in the person's body temperature, potentially resulting in adverse health consequences, such as heat exhaustion or heat stroke.
Various known garment features are available and used to assist athletes in coping with excess heat generated as a result of physical exertion. For example, mesh venting has been used in garments to help dissipate heat. In sports apparel, it is common to see underarm vents provided by very small or closed-hole meshes, or by small eyelets provided through the fabric. While helpful, such meshes or vents typically are too small or too impermeable to provide adequate cooling effects. Additionally, such vents typically are not large enough and/or located at targeted positions so as to provide improved cooling action.
Known garments or other athletic equipment also do little or nothing to help prepare an athlete for core body temperature increases that accompany an athletic event or exercise routine. In many instances, a garment and/or a training or preparation method that helps regulate core body temperature prior to, during, and/or after an event or exercise routine may be useful to improve or maximize the athlete's performance, e.g., by helping to cool the body to reduce core body temperature prior to the event, to slow the rate-of-rise in core temperature during the event, and/or to cool the body after the event.
Accordingly, it would be advantageous to provide apparel with targeted vented zones at targeted locations of the body to improve cooling action, and in many instances, to optimize and/or maximize the cooling action on the body. Such venting, in at least some instances, would improve the athlete's comfort and/or performance during the physical activity. Additionally, it would be advantageous to provide apparel and/or other athletic equipment and/or a preparation method that first anticipates the onset of heat stress and then enhances the body's thermoregulatory mechanism to function properly, e.g., to cool the body, before, during, and/or after the event or exercise routine.